Abstract

A high electrical resonator based on a superconductingcoil and a low loss capacitor has been realized and characterized at temperatures down to . The resonance frequency is near , and the quality factor is higher than . The main purpose of the experiment is to test the feasibility of cooling to ultracryogenic temperatures the readout of the gravitational wave detector AURIGA, which is based on a high resonant electrical matching network. The resonator current noise, measured by a superconducting quantum interference deviceamplifier, scales with temperature in the full range , showing that the system is thermal noise limited and its dissipating elements are well thermalized. Some implications of these results and possible applications are discussed.